Expert View and Suggestions of Use of EMG, TENS, Jaw Trackers and Digital Scanners

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I was invited by Dr. Sushil Koirala, Founder and Coordinator – MiCD Global Academy, Chief- Editor of MiCD Clinical Journal, as one of many globally renowned clinicians, academicians and researchers to answer 15 exclusive interview question for their clinical e-journal sharing my experience, clinical and research findings on the subjective of “TMDs – Confusion & Consensus: Expert’s Advice“. The following is the eleventh of 15 responses to their questions.

11. Kindly let our reader know your expert views and suggestions regarding the use of electro / digital diagnostic tools such as EMG, TENS, Jaw Vibration Analysis, Jaw Tracker, digital occlusal scanner (T-Scan / OccluSense), etc., in diagnosis, prevention, treatment, and monitoring of TMDs.

As we know most dentists in our profession have not learned how to measure the physiology or functional status of their patient’s jaws.  It was early on in my dental journey that I recognized there were many unanswered questions that teachers and leaders in the dental profession were not adequately addressing regarding dental occlusion.  In fact, they were avoiding the more complex restorative issues that impacted my patients who were having TMD pain, muscle dysfunction and joint derangement problems.

Because of my curiosity and interest to find better clinical answers, I saw the importance of using objective measuring technologies.  Quantifying and accurately measuring particular bio-physiologic parameters of my patient’s dental health like a researcher and scientist brought interest and intrigue to my practice that was formerly not realized. The quality of muscle rest, the functional ability for muscles to recruit when clenching, the balance of muscle response when teeth come together, mandibular positioning and location relative to a habitual centric occlusion, speed at which the mandible and the two condyles/disc system can open and close to an established terminal contact, any aberrant tongue swallowing patterns using computerized jaw tracking and joint sound recordings would add to the diagnostic clinical understanding. I wanted to know whether the TM joints were functioning in an unhealthy (pathologic) manner or functioning in a normal manner (quiet, no aberrant signature sound patterns).  These are just some of the many aspects of TMD that I discovered through my studies and research using technology.

I soon realized that quantified data (functional and dynamic) brought a new view point to the comprehensive examination process. It gave me a better understanding of the inner workings of the masticatory and temporomandibular joint system that I formerly didn’t realize.  It was the added K7 technology and dental TENS that allowed me to distinguish pathologic conditions from normal healthy physiologic conditions, especially if I wanted to really understand what TMD was about and whether the occlusion (bite) treatment provided to my patient was positively helping or was it negatively inducing TMD/occlusal problems.  I wanted to know the long-term effects.

I chose certain measuring technologies to help me discover better detailed answers rather than continue following the classical dogmas and assume the opinionated teachings I learned from others.

Questions I asked were:  Why do cusps fracture?  Why do veneers break or come off?  Why were my patients complaining of unresolving headaches, facial pains, jaw joint clicking and popping, ringing in the ears, ear congestion feelings, or having tender muscles on the side of their heads after seeing many specialists?  Or why was I seeing receding gum lines, bone loss and tooth wear facets, tooth mobility even after restorative or orthodontic treatment?  Why were patients who have seen numerous healthcare professionals, dentists, TMJ experts, orthodontists, and even after having extensive restorative treatment, still having problems?

Many of these patients who came to my office were wondering why they still had occipital tension, shoulder pains even after seeing many physical therapists, chiropractors, acupuncture, oral surgeons and other attempted treatments for their TMJ/TMDs. Many had worn numerous intra-oral appliances day-time and night-time splints that were not working for them. They reported clenching and unresolved grinding/bruxing of their teeth? These dental problems were not getting better, but in fact, were being ignored and excused by many professionals blaming the patient to have psychiatric stressors or emotional upsets that caused them to whine and complain about these mysterious problems. Medications were not working for them.  Why did my patients grind their teeth or brux even though they had airway evaluations and sleep studies that indicated otherwise, yet the patient found no resolution to their underlying issues?

I use the J5 dental TENS and the K7x Occlusal Evaluation system by Myotronics. The K7x system includes computerized mandibular scanning (CMS – Jaw tracking), electromyography (EMG), electrosonography (ESG). These technologies are FDA approved and ADA recognized. They are proven safe and effective aids in the diagnosis and treatment of TMD when used properly. As an analytical and curious clinical dentist, I was interested in learning how the masticatory system worked and functioned from a bio-physiologic perspective – beyond the mechanical.  An important note: Instrumentation does not diagnose, neither does it find the bite/occlusal relationship, but it definitely adds and aids in helping the clinician arrive at a proper cranio-mandibular disorders classification as well as aids the dentists in acquiring the proper occlusal relationship for diagnosis and treatment planning. It’s the dentists that needs to be trained and acquire the proper skills and understanding in the use of these instruments and interpretation of the measured data.

The following are general features I consider clinically important when choosing available electro-diagnostic and treatment technologies to do my research and clinical dentistry:

  1. I use technologies that could help me find a more reliable and stable jaw relationship/occlusion, to establish a physiologically stable position for the teeth, muscles and jaw joints. (Not all bio-electronic technologies do this).
  2. I want technology that accurately records (millimeters) my patient’s physiologic responses without digitally manipulating the raw data.  (Some technologies modified and electronically manipulate the raw data to make it look clean and impressive on the computer screen).
  3. I want jaw tracking technology that precisely and accurately records the occlusal relationships without occlusal interferences (millimeters) .
  4. I want technology to record muscle activity status as it really is without data manipulation when the patient relaxes their jaw and when they clench (microvolts).
  5. I want technology that records jaw joint sounds, position, location, duration and frequency patterns in real time (hertz). 
  6. I also want technology that documents and records cervical head posture – flexion/extension, lateral flexion and head rotations (millimeters).


I use Dental TENS to specifically break up proprioceptive muscle engrams (spastic muscle memory). This goes beyond the idea of just “relaxing muscles”.  Dental TENS produces an “involuntary” mandibular path of closure response which is key to why dental TENS is valuable for all those clinicians doing restorative or orthodontic occlusal therapy.  Note: Dental TENS is not a recording device.  I specifically use Myotronics K7x kineseograph to help me identify an optimal mandibular position using J5 Dental TENS muscle stimulus. Not all TENS units are the same.

An ultra-low frequency dental TENS (ULF TENS) unit should deliver a “simultaneous” and “bilateral” pulse. I have discovered through years of experience the J5 Dental TENS is more effective and accurate for physiologic bite registration.  Tracking the low frequency TENS pulse patterns using computerized mandibular scanning (K7x) can verify these patterns accurately.  (This is an important reason which most expert teachers miss and overlook). The ULF TENS should be a 3-electrode lead system rather than just two electrodes – This is important to relax not only the masticatory muscles, but also the cervical neck region. I find that this is a critical diagnostic and treatment tool (device) for establishing an optimal mandibular position for all TMD/restorative patients with problems. Note: the cervical neck region is a critical part of the mandibular masticatory system that should also be relaxed for optimal posture before a bite registration is recorded.  The J5 Dental TENS I use is able to effectively stimulate both the mandible and trapezius musculature simultaneously. The amplitude balance (left and right) controls the level of muscle stimulation.  Dental TENS can be observed with the simultaneous use of the K7x jaw track technology.

At our Occlusion Connections teaching center, we use Myotronics J5 Dental TENS and BNS-40 TENS units because of their capability in delivering a “simultaneous synchronous pulse bilaterally” unlike competing manufacturers that produce an alternating stimulus to the mandible. The Dental TENS units we use at OC are the patented 3-electrode lead system. Many within the neuromuscular arena do not realize the importance of these factor which aid in establishing muscle rest of both the masticatory and cervical neck region simultaneously. A frequency that has shown to be most effective by most muscle physiologist is a frequency below 2.0 Hz with a biphasic wave form stimulus between 150-500 milliseconds.  The J5 Dental TENS has this specific set frequency that stimulates every 1.5 seconds which makes it bio-physiologic and effective to use in the dental setting. (Note: I specifically do not use medical TENS since these kinds of devices are not designed for dental use).

Many TENS units are approved as a medical TENS device. But not all have FDA approval specifically for “Dental Use” nor are they all designed to function as a dental TENS device. Only Myotronics 4 channel J5 Dental TENS is approved for its intended use for: 1) treatment of TMD, 2) muscle relaxation and 3) physiologic bite registration.  Other TENS devices do not meet these criteria.  These are just some key reasons why I use these particular technologies in my practice.


I use and advocate the NEW K7x.  It is the 11th generation jaw tracking system developed by Myotronics over the last 51 years. The state-of-the-art K7x sensors provide a more stable and more accurate measurement to accurately record the dimensions and dynamics of the patient’s bite (occlusion), jaw movements in three dimensions as well as the posture/tilt of the head. 

The following should be considered in optimizing the use of neuromuscular instrumentation when using it to take a bite registration.

1) LEVEL OF ACCURACY – The K7x technology is set at a default gain of 1 mm when taking a bite registration. Competing technology display a default of 2-5 mm gain. Myotronics K7 active cursor on the monitor screen is shown to be stable and precise when no movement of their sensing device is still on the counter top.  This is important in regards to the level of accuracy when the clinician takes and records the bite registration. Having instrumentation that has the capability to take accurate bite registrations is one of the key reasons why I use this instrumentation. The technology should be able to synchronize EMGs with jaw tracking simultaneously and display it in real time on the same display rather than having to flip from window to window.

2) COMPREHENSIVE SENSORY ALIGNMENT FEATURE is critical to properly align each scan before data collection. Graphic representation of how to adjust the sensor is needed so the data is consistent and not compromised.

3) ELECTRICAL NOISE IMMUNITY – The K7x picks up virtually no system noise giving the clinician a true representation of the patient’s movements.  Data can be compromised because of excessive noise caused by poor systems design and inexpensive components used. The K7x has a 50/60 Hz notch filter and proprietary technology for maximum rejection of the EMI interference in the dental office. 

4) IMMUNITY TO MOVEMENT OF OBJECTS – The jaw tracking signal should not be susceptible/ “contaminated” by any movement of metal or non-metal objects (rings, watches, towel clips, dental instruments, etc.) that might not normally come within four feet of the patient nor by minor to moderate head motion.

5) MAXIMUM DEFLECTION of the cursors should not exceed 1 mm.  When the doctor’s hands are placed near the patient’s mouth and between the SENSOR ARRAY there should not be any deflective movement of the cursor.  The K7x has this capability.  Any motion of the operator around the system should not diminish the signaling.

Fine versus thick sweep lines are displayed while the patient is at habitual CO.  No noise should be produced when performing a no movement test in both the vertical, A/P and lateral dimensions. Velocity tracings on opening and closing cycles yield visually readable lines on the monitor to discern smooth versus sporadic movements of the jaw.

6) SENSITIVITY TESTING – There should not be any distortions of tracings when moving the hand within three feet of any sensor array. The K7x by Myotronics is extremely stable when comparing similar technologies based on personal experience and research.  When performing the sensitivity test it has been observed that any hand movement with objects or no objects produced stable, consistent, readable data on the monitor with no distortion.  This is again significant when taking a bite registration and collecting accurate data.


It is important to be aware, when investing in neuromuscular electro-diagnostic instrumentation, that low noise distortion in the wires and software is an integral factor in the quality and accuracy of data collection.  Line noise, external room interferences and sensor array distortion can influence data collection. This can produce flawed and inaccurate data and could lead to flawed data interpretation. Dentists who purchase this type of equipment should make sure that the data collected is noise-free, clear and easy to interpret with precision.  (Remember this is scientific research level technology that is used in the clinical setting).

1) SIMULTANEOUS EMG bite registration capability – this modality is a critical component to visualizing muscle activity in real time while using jaw tracking.  This feature is automated with the K7x technology, making this technology unique and desirable.

2) ELECTRICAL NOISE IMMUNITY – A necessity for consistent accurate data collection in order to discern between good data and environmental noise.  Some technology on the market today picks up 60 Hz noise along with the patient EMG activity.  This is unacceptable in a parameter where value lies in its accuracy.

3) EMG FUNCTIONAL CLENCH TEST – Real-time integration EMG capability is a must feature for easy discernable comparative tests and evaluation of muscle balance and muscle recruitment. The monitor display should have the ability to analyze the entire clench without converting from raw data to processed data.  (Important clinical feature for reconstruction/ TMD cases). This feature is a must when evaluating technology for clinical use.

4) EMG MONITORING MODE – This feature should be available to provide the clinician real-time bio-feedback to the patient and clinician.

5) OCCLUSAL PREMATURITIES IDENTIFICATION – A feature that is important to produce diagnostic data for clinical application for EMG balance and first tooth contact timing within 20-micron accuracy – It records and displays clinically relevant information beyond just interesting occlusal graphics.

6) SPECTRAL ANALYSIS on EMG to determine muscle fatigue is a unique feature available with K7x technology. EMG leads today are required to comply with FDA directives requiring “protected pins” on patient connected lead wires.  Rather than a “quick” fix” of gluing leads into the pre-amplifier, Myotronics technology has a history of complying with these stringent directives in spite of the costly changes in manufacturing costs. The K7x model has the new, safety connectors incorporated in the basic design.  When purchasing these kinds of instruments make sure the technology complies with FDA directives for dental patient safety and compliance.


1) BALANCED SOUND TRANSDUCER DIAPHRAGMS should be able to record clear, undistorted joint vibrations. 

2) UNOBSTRUCTED TRANSDUCERS – Transducers should be placed directly over the skin rather than a dome of solid silicon between the transducer and the skin which would reduce the ability to pick up soft sounds in the joint. It is imperative that this technology has the capacity to distinguish low frequency noise from high frequency noise, a significant feature in distinguishing joint noise diagnostically and accurately.

3) UNLIMITED FILTERING CAPABILITIES – The Myotronics Sonography has the capability to filter out loud joint sounds (clicks, pops, etc.) that might be masking the high frequency of degenerative joint disease sounds.  This gives the doctor a better picture of what is going on in the joint during function. Electro-sonographic technology should have the ability to read an entire range of joint sound vibrations.  Recording of both the low frequency joint vibrations as well as the high frequency joint vibrations at the same time should be available.  This will eliminate having to retake data, save time and avoids loss of good data.  The Myotronics electro-sonographic features have met these clinical concerns and challenges for my dental practice.

Using ESG transducers are easy for me and team to use when gathering important  jaw joint sound data and helps me arrive at a diagnostic craniomandibular classification of disc interference (Internal derangement) disorder accurately.  In my clinical practice when treating TMD cases, guessing and assuming things about jaw joints is not acceptable.

 BITE REGISTRATION APPLICATION – The Ultimate Evolution of  K7x Jaw Tracking and EMG Technology

We have chosen specifically the K7x since it is designed for clinical bite registration of TMD, fixed and removable prosthetic, orthodontics and diagnostic bite recordings. It was designed by clinical dentists for clinical ease and precision of optimal bite registration. The technology I use has the unique features of combining simultaneous three-dimensional real-time sweep and sagittal/frontal display of mandibular position with real-time graphic display of eight channel EMG for precise identification of the mandibular rest position and optimal myo-trajectory to determine a bite registration.

Any technology of this caliber should come complete with an automated bite recording capability for treatment that is automated to display a myo-trajectory (an involuntary mandibular closing path) with dental TENS.

1) PRECISE MARKING OF THE OCCLUSAL BITE POSITION – Necessary for easy-to-use Myocentric Targeting with graphic software that should allow precise placement of the occlusal bite position to within 0.1 mm precision prior to final bite registration.  (I can’t over-state the importance of this key feature for accuracy and precision).

2) RECORDING BITE REGISTRATION WHILE MONITORING EMGs – A visual display and data analysis of real-time EMG to ensure masticatory muscles status of the temporalis, masseter, digastric/suprahyoid and cervical group are key in distinguishing various types of neuromuscular problems.

3) SIMULTANEOUS JAW TRACKING AND EMG CAPABILITY to enable the doctor to guide the mandible to an optimum myocentric bite position while viewing the real-time EMG activity to insure optimally condylar/disc relationship and optimized musculature should not be overlooked.

4) FIRST TOOTH CONTACT EMG MONITORING MODE – Finishing the bite/ or adjusting the bite is critical for any restorative dentist.  Today’s technology should have EMG monitoring modes to guide the doctor to balanced occlusal contact force as well as musculature in both function and resting modes when implementing coronoplasty and or occlusal equilibrating techniques.  The K7x is the only technology that displays first tooth contact with simultaneous EMG to assist in identifying where to adjust the bite in micron levels.


Myotronics sensor array weight is 6 oz only.  It is attached via Velcro straps around the head to avoid direct contact to the mandible. 

1) WEIGHT OF THE SENSOR ARRAY is significant in that it can affect posture, patient comfort and impede muscle relaxation. The K7x sensor array passes the OC test of light weight compared to other heavier sensor arrays  on the market. Heavier weighted sensor array devices can be extremely uncomfortable for a TMD paining patient and is not conducive to patient relaxation and bite optimization. 

2) LOW INHERENT NOISE allows for a more accurate easier to discern diagnostic data.  Noise can be interpreted as patient information leading to an incorrect reading and diagnosis. 


The American Dental Association’s Council on Scientific Affairs has awarded surface electromyography (SEMG), computer mandibular scanning (CMS), and (ESG) Electrosonography its “Seal of Acceptance”, as diagnostic aids in the management of temporomandibular and occlusal disorders. The U.S Food and Drug Administration has granted 510K status to each of these mentioned devices for use in the diagnosis and management of musculoskeletal occlusal disorders.

These are just some of the key reasons why I have use Myotronics K7x Occlusal Evaluation System.

Note of Disclosure: I have no proprietary, financial or other personal interest of any nature or kind in advocating Myotronics K7x, product or services that are discussed or presented in these writings.


I am familiar with various digital occlusal systems. They have been found to be helpful to some clinicians. I believe from experience that the thickness or thinness of these digital occlusal wafers effects the way a patient occludes and positions their mandible. From experience one realizes when biting down on various density of foods or materials the mandible reacts accordingly, altering the six-dimensional jaw position. The dentist must recognize that manufacturers of these devices have different parameters of what they consider accurate and precise when displaying and recording bite force and timing information.

The question I believe every occlusally-minded dentist should ask when considering to invest into these types of devices is: 1) How accurate do you believe a patient’s occlusion (bite) should be? 100 microns accurate? 60 microns accurate? 40 microns or 20 microns or less?  The thickness of these wafers matters and does affects how the occluded data is registered in the six-dimensions of occlusion.  2) A key question to ask is: What mandibular position (location) is the digital occlusal technology measuring when equilibrating or adjusting the patient’s occlusion?  Think of the six mandibular dimensions of occlusion. Regardless of what occlusal technique or technologies used I have learned that no electronic technologies adjust the occlusion. The doctors knowledge, understanding, skill and judgement does the occlusal adjustments based in information he/she understands.

I have the OccluSense which is a 60-micron thin digitized wafer. Other manufacturers offer a 100-micron wafer.  Both accurately record to the level that they are intended for their use. It is unclear as to what level of filtering settings is best when trying to interpret the accuracy of the displayed premature occlusal contacts with these technologies.

The OccluSense wafer does record at a 60-micron level showing red articulating paper markings that are also transferred onto the occlusal surfaces like traditional articulating paper along with occlusal force data displayed on an iPad.  The 60 micron red digital marking paper wafer does transfer marks all over occlusal surfaces making it a real challenge for any dentist to figure out what red mark they should adjust/grind away and which one they should not touch. There is no calibrated ruler to determine what level of bite force pressure is clinically relevant, so sliding the vertical filtering is but a clinical guess and best subjective judgement based on the clinicians understanding and awareness about occlusal details.  Perhaps some dentist may not be aware of the significance of these occlusal details.

Any dentist who is not really trained in coronoplasty or micro adjustments will most likely just start grinding down inadvertently whatever high spots they think are the problematic spots based on what they think they are seeing on the OccluSense iPad recordings. This can be a real problem for both the doctor and patient when the bite may appear even and balanced, but to the patient their bite may not feel comfortable. This has been proven to be a real dilemma for many patients who have experience this type of occlusal equilibrating adjustments.

The dentists must learn and acquire the skills to adjust occlusion correctly. Technologies only can give information, but they cannot diagnose, treat nor adjust your patients.  The doctor must learn how to properly interpret what the data means from these technologies and the doctors must learn how to adjust the bite in the correct mandibular position to avoid further TMD and occlusal problems regardless of technologies used.

Clayton A. Chan, D.D.S. – Founder/Director

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